It should also be noted that it is possible to package a share-config-custom.xml file in a JAR or AMP. In this way you can have multiple share-config-custom.xml files packaged in JARs or AMPs if necessary. JARs will be loaded from the classpath, for example ./tomcat/shared/lib. AMPs will be applied to the Share WAR file.
Another key Share configuration file is slingshot-application-context.xml which can be found at tomcat/webapps/share/WEB-INF/classes/alfresco/slingshot-application-context.xml in the default SkyVault installation. This loads a number of other configuration files:
<!-- Spring Web Scripts -->
<value>classpath:org/springframework/extensions/webscripts/spring-webscripts-config.xml</value>
<value>classpath:META-INF/spring-webscripts-config-custom.xml</value>
<value>jar:*!/META-INF/spring-webscripts-config-custom.xml</value>
<!-- Spring Surf -->
<value>classpath:org/springframework/extensions/surf/spring-surf-config.xml</value>
<value>classpath:org/springframework/extensions/surf/spring-surf-config-remote.xml</value>
<value>classpath:META-INF/spring-surf-config-custom.xml</value>
<value>jar:*!/META-INF/spring-surf-config-custom.xml</value>
<!-- Surf Autowire Support -->
<value>webapp:WEB-INF/surf.xml</value>
<!-- Common form config -->
<value>classpath:alfresco/form-config.xml</value>
<!-- Share default config -->
<value>classpath:alfresco/share-config.xml</value>
<!-- Share help url config -->
<value>classpath:alfresco/share-help-config.xml</value>
<!-- Share form config -->
<value>classpath:alfresco/share-form-config.xml</value>
<!-- Share Document Library config -->
<value>classpath:alfresco/share-documentlibrary-config.xml</value>
<!-- Share Data List form config -->
<value>classpath:alfresco/share-datalist-form-config.xml</value>
<!-- Share workflow form config -->
<value>classpath:alfresco/share-workflow-form-config.xml</value>
<!-- Share CMIS config -->
<value>classpath:alfresco/share-cmis-config.xml</value>
<!-- Share Security config -->
<value>classpath:alfresco/share-security-config.xml</value>
<!-- Share custom config -->
<value>classpath:alfresco/web-extension/share-config-custom.xml</value>
<value>jar:*!/META-INF/share-config-custom.xml</value>
<value>classpath:alfresco/web-extension/share-config-custom-dev.xml</value>
<value>jar:*!/META-INF/share-config-custom-dev.xml</value>
Note that the custom configuration files are loaded last, so that they can override existing configuration.